Lawman did mention that Denis had enumerous hat-tricks, but 18 is an absurd number.
So in the 237 goals that he scored, 54 were in games that he scored hat-tricks, witch means that 23% of his goals made part of hat-tricks. Shocking.
Trully a LEGEND.

What is heartbreaking there is that 22 of those goals where scored in the season we sold him for nothing, and to add further insult to injury our top score for the season was Sammy Mcilroy who managed to find the net a monumental 6 times in all competitions - 6 versus 22 thanks for nothing Docherty

Even worse is the fact that Denis scored 6 goals in the first half for City against Luton Town in the Cup, the match was abandoned just on 50 minutes and in the replayed fixture City lost 3-1, with Denis scoring their only goal

The feat is not in the record books sadly only as a trivia question now

Unfortunately other than Martial I don't see any of the current players(Rooney excepted obviously) who are likely to join the multiple hat trick club any time soon and Martial probably won't before next season at the earliest.